|Publication number||US7997149 B1|
|Application number||US 12/950,373|
|Publication date||Aug 16, 2011|
|Filing date||Nov 19, 2010|
|Priority date||Nov 19, 2010|
|Also published as||CN103080740A, CN103080740B, EP2641081A1, WO2012067676A1|
|Publication number||12950373, 950373, US 7997149 B1, US 7997149B1, US-B1-7997149, US7997149 B1, US7997149B1|
|Original Assignee||Hema-Q, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (1), Classifications (4), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to an apparatus and method for non-invasively measuring the sound velocity of a fluid flowing in flexible or rigid tubing.
The term “sound velocity” is a recognized shorthand expression describing a characteristic of the speed at which sound waves travel in a medium. The speed of sound varies depending on the medium through which the sound waves pass. It usually is a parameter used in describing properties of different substances or mediums. Knowing the value of the sound velocity of a particular medium, such as a flowing fluid, liquid or gas, permits many different characteristics or properties of the fluid to be determined. Using the sound velocity together with appropriate mathematical relationships allows for determination of various characteristics or properties of the medium such as its density, purity concentration, components of the medium composition, etc.
Several different types of apparatus exist for measuring the sound velocity in a fluid flowing in flexible or rigid tubing. The term “tubing” is used hereafter to define both the flexible, semi-rigid, and rigid type. Flexible tubing is of a material, such as an elastomeric, that can be deformed. Rigid tubing can be of any material such as plastic or metal and is not normally deformable. Semi-rigid tubing can be of a material other that an elastomeric that can be somewhat deformed.
Apparatus for measuring sound velocity is generally of either the contact or non-invasive type. In the contact type, some part or parts of the measuring apparatus come into direct contact with the fluid. In the non-invasive type, the sound velocity is measured without any part of the measuring apparatus coming into contact with the fluid. Whatever apparatus is used for measuring the sound velocity, it is desired that it be as simple in construction and operation as possible and that it does not adversely hinder or affect the application or other apparatus with which it is being used.
In accordance with the invention, an apparatus is provided to measure sound velocity in a fluid flowing in either elastic, semi-rigid or rigid tubing that is in-line with the tubing and which can operate on a continuous basis. In the invention, a capsule or cartridge is provided that is placed in the tubing line. That is, the cartridge is between two ends of the tubing and the fluid flows from one end of the tubing, through the cartridge and into the other tubing end to its ultimate destination. The cartridge has a generally cylindrical with two internal chambers of different diameters through which the fluid flows. The two different internal chamber diameters form two walls spaced apart by a fixed distance that are generally transverse to the cartridge longitudinal axis, which is the direction of the fluid flow. The two walls define reflecting points for a signal of ultrasonic energy.
The cartridge has a single transducer, or sensor, for transmitting and receiving the ultrasonic signal under control of a microprocessor. The apparatus operates using a pulse echo technique in which the round-trip transit time of the signal transmitted by the sensor to each of the two reflecting walls and reflected back to the sensor is measured. The microprocessor operates to make the two round-trip transit times measurements and uses these together with the known value of the distance between the two reflecting walls to calculate the sound velocity of the flowing fluid.
The cartridge of the invention used in making the sound velocity measurement is relatively inexpensive. Therefore, it can be part of a disposable tubing set used in a sterile application, such as in a medical procedure. The cartridge can be adapted to be utilized with any one of flexible, rigid or semi-rigid tubing of any type of material requiring only the appropriate arrangement for coupling ends of such tubing to the ends of the cartridge in a fluid type manner.
Other objects and advantages of the present invention will become more apparent upon reference to the following specification and annexed drawings in which:
The hollow interior of the cartridge 10 has two generally cylindrical tubular sections or chambers 20A and 20B of different diameters, with the downstream section 20A having a smaller diameter than that of the upstream section 20B. These two internal sections 20A and 20B communicate with internal passages 22A and 22B at the cartridge ends 12 and 14 so that the fluid can flow freely through the cartridge interior along its longitudinal axis.
The cylindrical sections 20A and 20B form two walls 24A and 24B that are generally transverse to the cartridge longitudinal axis. The two walls 24A and 24B are spaced apart by a known fixed distance L. An ultrasonic transducer (sensor) 30, such as a piezoelectric crystal, is mounted at the upstream end of the cartridge hollow internal cylindrical section 20B adjacent to where the fluid enters the cartridge. The sensor 30 can be of any suitable material such as PZT and PVDF, as is well known in the art. As seen in
The assembly of the sensor 30 and base piece 32 are sealed into the cartridge. The cartridge can be manufactured in two longitudinal halves, such as by plastic molding or machining. The sensor 30 and base piece 32 are mounted to one of the halves which are then joined together and the exit for the leads 34 sealed to form a cartridge which is fluid tight to the fluid that flows through it.
In operation of the apparatus, by a circuit described below, the sensor 30 transmits ultrasonic energy signals which are reflected from each of the walls 24A and 24B back to the sensor 30. The round-trip times for the signals will be different due to the different distances of the respective walls 24A and 24B from the sensor 30. The sound velocity V of the fluid flowing in the cartridge is calculated from the two measured round-trip transit times and the known fixed distance L between the two walls 24A and 24B. This is shown as follows:
V is the sound velocity,
ta is the round trip transit time of the signal from the sensor to the first wall 24A,
tb is the round trip transit time of the signal from the sensor to the second wall 24B, and
L is the fixed known distance between the first and second walls 24A and 24B.
It can be seen that:
Since LA−LB=L which is known, then
The bursts of pulses that the sensor receives from the transmit control circuit 44 are converted to electro-mechanical energy and transmitted by the sensor 30 to be reflected back to the sensor from the walls 24A and 24B. The sensor converts the reflected received energy signals to electrical signals which are applied to a high speed amplifier 52. The signals passing through the high speed amplifier 50 are applied to a high-speed analog to digital (A/D) converter 52 and the digital output is applied to the microprocessor 40. Preferably, there is a feedback control circuit 54 between the microprocessor and the high-speed amplifier 50 to normalize the amplitude of the amplifier output signals and thereby the amplitude of the A/D converter output signals applied to the microprocessor.
The times that the reflected signals from the two walls 24A and 24B will be received by the sensor 30 are different, because the walls are at different distances LA and LB from the sensor. The distances LA and LB are known from cartridge manufacturing specifications and programmed in the microprocessor. Since the approximate times of reception of the signals from each of the two walls is known, the microprocessor establishes a window at two different reception times for the respective signals reflected from the walls 24A and 24B.
Since the microprocessor knows the time of transmission of the signals by the sensor 30 and it knows the time of reception of the signals reflected from each of the walls 24B and 24A it calculate the two different round-trip transit times tb and ta. The microprocessor also is programmed to calculate the difference ta−tb between the two transit times. Further, having been preprogrammed with the value of the known fixed distance L, the microprocessor can easily calculate the value of the fluid sound velocity V using equation (5).
Typical dimensions for the cartridge and specifications for the electronics are:
Overall length of cartridge
3.0″ or less to 12.0″ or more
0.55″ to 10.0″
0.50″ to 10.0″
0.05″ to 6.0″ or more
Frequency of signal applied to sensor
1.0 MHZ to 20.0 MHZ
Duration of signal bursts
100 nanosec to 10 microsec
Repetition rate of signal busts
10 microsec to 20 millisec
The internal and external dimensions of the cartridge and the frequency and characteristics of the signals are selected to best address the particular application in terms of type of fluid, size of the tubing, etc.
Specific features of the invention are shown in one or more of the drawings for convenience only, as each feature may be combined with other features in accordance with the invention. Alternative embodiments will be recognized by those skilled in the art and are intended to be included within the scope of the claims. Accordingly, the above description should be construed as illustrating and not limiting the scope of the invention. All such obvious changes and modifications are within the patented scope of the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4262523 *||Nov 22, 1978||Apr 21, 1981||The Solartron Electronic Group Limited||Measurement of fluid density|
|US4622202 *||Aug 2, 1983||Nov 11, 1986||Hitachi, Ltd.||Reactor in-vessel sensor and core monitoring apparatus|
|US7838296||Aug 28, 2002||Nov 23, 2010||Separation Technology, Inc.||Methods and apparatus for ultrasonic determination of red blood cell indices|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8714017||Nov 15, 2011||May 6, 2014||Hema-Q, Inc.||Apparatus for non-invasive determination of sound velocity in a liquid and determining a parameter of the liquid from the sound velocity|
|Apr 2, 2011||AS||Assignment|
Owner name: HEMA-Q, INC., NEW YORK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DAM, NAIM;REEL/FRAME:026064/0297
Effective date: 20110331
|Jan 6, 2015||FPAY||Fee payment|
Year of fee payment: 4